Runner-impeller for turbine pump



Dec. 5, 1967 R. s. SPROULE 3,356,035

RUNNER-IMPELLER FOR TURBINE PUMP Filed Aug. 51, 1965 INVENTOR I ROBERTS. SPROULE ATTORNEYS United States Patent 3,356,035 RUNNER-IMPELLER FORTURBINE PUMP Robert S. Sproule, Montreal, Quebec, Canada, assignor toDominion Engineering Works Ltd., Montreal, Quebec,

Canada Filed Aug. 31, 1965, Ser. No. 483,925 4 Claims. (Cl. 103-98)ABSTRACT OF THE DISCLOSURE The runner of a hydraulic machine of theFrancis type is surrounded by an annular blade array mounted for freewheeling rotation about the main runner when operating as a turbine, andsecurable to the runner to increase the effective runner diameter whenthe machine operates as a pump.

The present invention relates to rotary hydraulic machines and moreparticularly to pump-turbines in which the runner-impeller is soconstructed that it is of relatively small diameter when acting as aturbine and is relatively larger in diameter when acting as a pump.

It has long been desired to utilize a rotary fluid machine either as apump or as a turbine, selectively, and at different times. Such amachine is called a pump-turbine. When operated as a pump, it is drivenby an electric motor and when operated as a turbine, it drives theelectric motor which then functions as a generator.

One of the problems associated with a pump-turbine is that when themachine operates as a pump, the linear peripheral speed of the impellermust be higher than the linear peripheral speed at which it operates asa turbine for reasonable efficiency. However, under both operatingconditions the rotational speed must remain constant, for use with asingle speed motor-generator.

The prior art has recognized this particular problem and has providedseveral proposed solutions. One such proposed solution'was to provideboth a motor and a generator having means to alternately connect them tothe pump-turbine, the motor being designed to operate at a differentconstant speed from that of the generator. This solution has thedisadvantage of being overly expensive, since it required two electricalmachines and had a further disadvantage of requiring complex couplingdevices.

Another proposed solution was to provide a specially constructedmotor-generator capable of operation at two speeds. However, thissolution has proven undesirably expensive due to the necessary addedcost for the special motor-generator.

Another problem associated with such rotary fluid machinery is theinability to operate a turbine over wide variations of hydraulic heads.Prior art systems were proposed which provided two interchangeablerunners or impellers which were intended to be used depending on thediffering hydraulic heads. This proposal is not satisfactory since itrequires the manufacture of an additional runner or impeller and alsorequires that the unit be shut down for a considerable length of timewhile the runner or impeller is changed: this is uneconomic. Furthermorethese systems are only partially successful and cannot be utilized in apump-turbine installation as they are restricted to either pumps orturbines.

The principal object of the present invention is to provide an improvedpumptu-rbine wherein the motorgenerator operates at a constant speed andwherein the higher constant speed for pumping is obtained by increasingthe overall diameter of the runner-impeller, thus effecting a higherlinear speed at its periphery.

Another object of the present invention is to provide 3,356,035 PatentedDec. 5, 1967 a pump-turbine which does not embody difficult engineeringand constructional problems and is of relatively low cost.

A further object of the present invention is the provision of apump-turbine capable of efficient use within a wide range of hydraulicheads.

A still further object of the invention is the provision of apump-turbine which may be readily and easily changed from one mode ofoperation to the other.

A still further object of the present invention is to provide apump-turbine which requires only a very short downtime for changing itsmode of operation.

The present invention provides a runner-impeller in which the outerportion is of larger diameter and is constructed as a separate piece,said separate piece being annular and comprising blade portions andportions of the shrouds. This separate annular portion is called afree-wheel.

When the machine operates as a pump, the rotation is in one directionand the free-wheel is attached to and is driven by the mainrunner-impeller.

However, when the machine operates as a turbine, the rotation is in theopposite direction and the main runnerimpeller is disengaged and runsaway from the freewheel. The free-wheel portion automatically assumes aspeed lower than the synchronous speed of the machine, that is, thespeed where it presents the least intereference to the water coming fromthe distributor to the main runner-impeller. The blade area of the mainrunner-imeller is adequate to develop the power of the water, and theradius of the leading edge of its blades is chosen for optimumefficiency and power as a turbine, with due allowance being made for theunavoidable interference of the free-wheel.

The construction and operation of a rotary hydraulic machine inaccordance with the present invention will be further understood,together with further objects and advantages thereof from the followingspecifications and drawings wherein:

FIG. 1 is a fragmentary radial vertical section of a rotary hydraulicmachine incorporating the preferred execution of the invention.

FIG. 2 is a fragmentary radial vertical section of a rotary hydraulicmachine incorporating an alternative execution of the invention.

Referring now to the drawings wherein like or corresponding parts havelike or corresponding reference numerals and with particular referenceto FIG. 1, when the machine operates as a turbine, water under pressurepasses from the inlet casing 10 to a distributor 11, flows through thefree-wheel assembly shown generally at 12 and thence to the mainrunner-impeller shown generally at 13; the water is then discharged at areduced pressure into draft tube 14. Main runner-impeller 13 comprisesblades 15 which are connected together by a crown or upper shroud 16 anda lower or band shroud 17; shaft 18 is rigidly secured to crown shroud16. The end of shaft 18 remote from crown shroud 16 is coupled to amotor-generator (not shown).

When the machine operates as a pump, shaft 18 is rotated by themotor-generator which rotates the main runner-impeller assembly 13. Forthis mode of operation the free-wheel assembly 12 is rigidly attached toassembly 13, the direction of rotation is then reversed and the flow ofwater is from draft tube 14 to casing 10.

The rotating assembly comprising free-wheel 12, runnerimpeller 13 andshaft 18 are enclosed within upper stationary structure 19 and lowerstationary structure 20.

To locate and support free-wheel 12 when it is disconnected from mainrunner-impeller assembly 13, an annular bearing pad 21 is provided, saidbearing pad being attached to the lower stationary structure by means ofa series of bolts 22, only one of which is shown.

The free-wheel assembly 12 comprises an upper shroud 23, a lower shroud24, said shrouds being separated from each other by a series ofcontoured blades similar in number to blades 15 of the mainrunner-impeller 13.

i The crown shroud 16 of runner-impeller 13 has an extension 26 whichsubstantially overlaps upper shroud 23 of free-wheel 12, and the freeedge 27 of band shroud 17 is substantially in line with the lower shroud24 of free-wheel 12.

The upper shroud 23 of free-wheel 12 is provided with a series ofcountersunk holes 28 and extension 26 has a similar matching number ofthreaded holes 29. When it is desired to operate the machine as a pump,free-wheel 12 and runner-impeller 13 are unitized by means of a seriesof fasterners such as bolts, said bolts passing through countersunkholes 28 then into threaded holes 29. When it is desired to operate theunit as a turbine, these bolts are removed and the free-wheel assembly12 is thereby freed from the runner-impeller 13.

It will be seen by referring to the foregoing description that as aturbine designed for variable heads, the unit will function as follows:Under high head, the velocity and direction of water flow from thedistributor is such that it imparts torque in the proper direction tothe free-wheel assembly 12, rotating said free-wheel at the synchronousspeed of the machine. This water in turn imparts torque to the mainrunner-impeller 13 and hence to the generator (not shown).

At low heads the velocity and direction of the water flow is such thatif the free-wheel assembly 13 is rotated at the synchronous speed itwould receive torque in the wrong direction therefore it is left free torotate at a lower speed and thus rotates torque free between thedistributor 11 and the main runner-impeller 13.

Referring now to FIG. 2 which shows an alternative embodiment of theinvention, band shroud 17 is extended to form a lip shaped protrusion 30on which a bearing 31 is formed. Bearing 31 locates and supports thelower shroud 24 of free-wheel 12. The upper shroud 23 of free-wheelassembly 12 is located by an upper bearing 32 which in turn is attachedto a stationary extension 33, said extension 33 being rigidly attachedto the upper stationary structure 19.

Splines 34 are formed on the inner edge of upper shroud 23 of free-wheelunit 12 and splines 35 are provided on the outer edge of therunner-impeller crown shroud 16, splines 34 and 35 being in face to facerelationship. A key 36 or a series thereof is provided to lock togethercomponents 12 and 13 when it is desired to run the unit as a pump. Itwill be understood that key 36 may be inserted into and disengaged fromsplines 34 and 35 by any suitable means, either manually or by anymechanical aid.

It will be seen that I have provided an improved pumpturbine of low costwhich presents no difficult engineering or constructional problems. Itis capable of eflicient use within a wide range of heads, and in bothembodiments the unit may be readily changed from one mode of operationto the other. Further, the pump-turbine of the present inventionrequires only a short shut down period for conversion from one mode ofoperation to the other.

It will be obvious to those skilled in the art that various changes maybe made without departing from the spirit of the invention and thereforethe invention is not limited to what is shown in the drawings anddescribed in the specification but only as indicated in the appendedclaims.

What is claimed is:

1. In a fluid machine, a shaft, a pair of inner spaced shrouds havingblades between them connected to said shaft for rotation therewith, afree-wheel unit outwardly of said inner shrouds and blades andcomprising a pair of outer spaced shrouds respectively and generally inline with the free edges of said inner shrouds, said free-wheel unitfurther comprising blades between said outer shrouds, bearing meansjournaling said free-wheel unit, a said inner shroud having splines atits outer edge, a said outer shroud having splines at its inner edge injuxtaposition with said first-mentioned splines, and movable key meansselectively engageable with said splines.

2. The fluid machine of claim 1, and motor means for moving said keymeans.

3. The fiuid machine of claim 1, said other of said inner shrouds at theouter periphery thereof supporting said bearing means.

4. In a rotary turbo machine having a shaft, a main runner connectedthereto having at least one shroud member, a plurality of bladesattached to said shroud member arranged relative to a portion of themachine casing for passage of working liquid therethrough in energytransfer relation with the runner, the improvement comprising a freewheel unit having an array of blades arranged in the form of an annulusinterposed in the liquid passage radially outwardly of said runnerbetween the casing and the runner and axially aligned therewith forinteraction with the working liquid on passage through the runner, saidfree wheel blades being supported by a hubless-annular shroud member,bearing means supporting said shroud member for rotation independentlyof said main runner, and interlocking means between the peripheral edgesof said shroud members for selective connection and disconnection ofsaid free wheel unit with said runner when operating as a pump and aturbine respectively.

References Cited UNITED STATES PATENTS 2,203,843 6/1940 Pierce 2301312,784,936 3/1957 Schmidt 253---117 3,208,389 9/ 1965 Stefan 1()3-98FOREIGN PATENTS 1,124,752 10 1956 France.

564,826 11/1932 Germany.

HENRY F. RADUAZO, Primary Examiner.

1. IN A FLUID MACHINE, A SHAFT, A PAIR OF INNER SPACED SHROUDS HAVINGBLADES BETWEEN THEM CONNECTED TO SAID SHAFT FOR ROTATION THEREWITH, AFREE-WHEEL UNIT OUTWARDLYY OF SAID INNER SHROUDS AND BLADES ANDCOMPRISING A PAIR OF OUTER SPACED SHROUDS RESPECTIVELY AND GENERALLY INLINE WITH THE FREE EDGES OF SAID INNER SHROUDS, SAID FREE-WHEEL UNITFURTHER COMPRISING BLADES BETWEEN SAID OUTER SHROUDS, BEARING MEANSJOURNALING SAID FREE-WHEEL UNIT, A SAID INNER SHROUD HAVING SPLINES ATITS OUTER EDGE, A SAID OUTER SHROUD HAVING SPLINES AT ITS INNER EDGE INJUXTAPOSITION WITH SAID FIRST-MENTIONED SPLINES, AND MOVABLE KEY MEANSSELECTIVELY ENGAGEABLE WITH SAID SPLINES.